In order to reshape tubes by rod drawing, one end of a tube must be prepared appropriately for attachment to drawing tongs. During rod drawing with a slide or floating mandrel, this mandrel must also be fitted with precision into the end of the tube. Such preparatory measures are usually done manually to a large extent and carried out with no or little automation.
Solutions are known from the practice of rod drawing whereby the slide mandrel is first introduced by a machine into the tube, after which indentations are formed in the tube casing simultaneously behind and in front of the inserted mandrel. Before insertion of the mandrel, strict requirements must be met with regard to the perpendicular alignment of the tube end, which must often be done manually.
The use of an apparatus according to the invention preferably, but not necessarily, relates to tubes made of a relatively soft metal such as copper, for example. The use of a slide mandrel in the tube and a die outside reduces the tube's wall thickness while imparting to it an exact inside and outside diameter.